The Truth About Dairy and Strong Bones

08/17/2017
WELLNESS
By Anne Cain

Dairy foods play an important role in children’s growth and development in many ways, but one of the most important is developing strong and healthy bones. The adage “drink milk for strong bones” is so familiar that the advice is often taken for granted. Perhaps it’s time to take another look at the importance of dairy because the incidence of rickets in children is on the rise, bone fractures in adolescents are becoming more frequent and osteoporosis is becoming a common condition in the elderly population.

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It’s time to take a new look at dairy’s role in the bone health of children and youth and why building strong bones at an early age is so important.

Dairy is the Key to Strong Bones

Healthy bones need the mineral calcium to become and stay strong. Including calcium in your diet is as easy as reaching into the dairy case. In fact, six of the top 10 food sources of calcium are dairy foods. Plain low-fat yogurt is the top source with 400 mg per eight-ounce serving, followed by Cheddar cheese, mozzarella cheese and two percent milk. 

In addition to calcium, bones need vitamin D, which helps the body absorb calcium. Most people get vitamin D from three sources:

  • Sunlight:  Being outside in sunlight about 15 minutes a few times a week helps the body to make vitamin D.
  • Fortified milk: Most varieties of milk are fortified with vitamin D. According to the National Dairy Council, one cup of milk provides nearly one-third the daily requirement of vitamin D.
  •  
  • Foods: Only a few foods contain naturally occurring vitamin D: cod liver oil, egg yolks, fatty fish such as salmon and certain varieties of mushrooms such as maitake and portabella that are exposed to ultraviolet light.

For children, milk is the number one food source of both calcium and vitamin D. However, by age six, research shows that children do not receive the recommended number of servings from the dairy group. The 2015 Dietary Guidelines for Americans recommend two cups for children ages two to three years, two and one-half cups for children ages four to eight years, and three cups for teens, ages nine to 18 years. While yogurt and cheese are good sources of calcium, they are not typically fortified with vitamin D.

Flavored is Fine

Flavored milks, such as chocolate and strawberry, contain the same essential nutrients as white milk, including calcium and vitamin D. Studies show that children who drink flavored milk meet more of their nutrient needs than non-milk drinkers and do not consume more added sugar, fat or calories. When it comes to bone health, any flavor is fine.

Bone Building Starts Early

Bone mass, or bone density, is the best way to determine the health of bones. Bone mass potential is largely determined by genetics, but 20 to 40 percent of an adult’s peak bone mass is determined by lifestyle choices, such as diet and physical activity. A recent joint statement of the National Osteoporosis Foundation and the American Society for Nutrition states the importance of developing strong bones in childhood and early adulthood because the bone mass attained early in life is a predictor of osteoporosis — the disease characterized by porous or brittle bones — later in life. In other words, osteoporosis is a childhood condition with adult consequences.

The onset of puberty and the adolescent growth spurt is a time of rapid bone formation and reaches a peak around 12.5 years of age in girls and 14 years in boys. Within four years after that growth spurt, the adolescent has achieved 95 percent of his or her adult bone mass. This period of rapid growth provides the best opportunity to influence peak bone mass, but it is also the time when adolescents are most vulnerable to fractures because the bones become temporarily more fragile as linear bone growth is occurring faster than bone mineralization. Adolescents who are not getting enough calcium or vitamin D may be even more vulnerable to fractures. 

“Drinking milk is one of the most important habits children and teens can do for their general health,” says Dr. Lisa Corum, family physician at KentuckyOne Health®. “Milk not only improves their nutrient intake now, but also helps them develop a strong skeleton for the adult years.”

The Return of Rickets

Rickets is the softening and weakening of bones in children due to extreme and prolonged vitamin D deficiency. Vitamin D was first added to milk in the 1930s to help prevent rickets in children, which led to the near eradication of this disorder in the United States. However, a recent study conducted at the Mayo Clinic found that the incidence of rickets has dramatically increased since 2000.  Children and adolescents who overuse sunscreen, do not play outside or do not consume enough vitamin D through milk and other food may increase their risk of rickets, according the National Institutes of Health.  One cup of milk provides nearly one-third the daily requirement of vitamin D for those nine years and older, and only cost approximately 25 cents per cup. 

Rethink the Drink

With so many beverage choices available to students, including sugary sodas, sports drinks and energy drinks, milk is often replaced with beverages that have substantial amounts of added sugar and little nutritional value. By age six, the average consumption of milk, yogurt and cheese falls below recommended amounts and this trend continues through the teenage years and into adulthood as students become responsible for making their own beverage choices. To make dairy more appealing, the industry is developing innovative packaging options, eye-catching labels and new flavors — all with students in mind. 

In a world with so much conflicting nutrition advice, parents and teachers can be reassured that drinking milk and consuming dairy products now provides all students from pre-school to high school with the best way to decrease the risk of fractures and to prevent having brittle bones as an adult. 

Anne Cain, MS, MPH, RDN, is Director of Communications with Southeast United Dairy Industry Association.
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Issue 19.1 | Summer 2017

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